17438-14-1Relevant academic research and scientific papers
Aqueous CO2fixation: construction of pyridine skeletons in cooperation with ammonium cations
Fan, Weibin,Guo, Shiwei,Huang, Deguang,Li, Yinghua,Xiang, Shiqun,Zhang, Wei
supporting information, p. 7950 - 7955 (2021/10/29)
A simple and green method is explored for the synthesis of fused pyridines by [2 + 2 + 1 + 1] the cycloaddition of ketones with an ammonium cation under a CO2atmosphere. The reactions employed ammonium cation as a nitrogen source and CO2gas as a carbon source in an aqueous solution. Monoethanolamine (MEA) was used as an additive to increase the solubility of CO2in an aqueous solution. The scope and versatility of the method are demonstrated with 38 examples. Products are found to be photosensitive and show potential applications as organic optoelectronic materials. A selectfluor-promoted reaction mechanism is proposed based on the experimental studies. Our work is superior as it is a metal-free system, uses CO2as a carbon source and MEA as an additive in aqueous synthesis.
1,4-Dihydropyridine/BF3OEt2 for the reduction of imines: Influences of the amount of added BF3OEt2 and the substitution at N-1 and C-4 of the dihydropyridine ring
Zattoni, Ingrid F.,Guanaes, Lais D.,Cerqueira, Letícia B.,Pontarolo, Roberto,Ducatti, Diogo R.B.,Duarte, M. Eugênia R.,Noseda, Miguel D.,Trindade, Angela C.L.B.,Gon?alves, Alan G.
supporting information, (2019/09/12)
We have evaluated four 1,4-dihydropyridines (DHPs 1a, 1b, 1c and 1d) as reducing agents, which presented free (hydrogenated) or phenyl-substituted N-1 and C-4 positions of the DHP ring. Reactions combining each of the DHP and different amounts of BF3OEt2 were evaluated for the reduction of imine 2a (N-benzylideneaniline). DHP simultaneously substituted at N-1 and C-4 (1a), and DHP substituted at C-4 (1b) gave lower yields for reduction of 2a in comparison with DHPs 1c and 1d (both unsubstituted at the C-4 position). By evaluating the amount of added BF3OEt2 to the reaction mixture, we have found that DHP 1c (substituted at N-1) provided its best yield for amine 3a (82%) when associated with stoichiometric amounts BF3OEt2, while DHP 1d (N-1- and C-4-unsubstituted derivative) was more effective (90% yield) with catalytic quantities of the Lewis acid. The reaction system using DHP 1c under stoichiometric BF3OEt2 could also be successfully applied with additional imine examples and under reductive amination conditions.
Organocatalyzed biomimetic selective reduction of c=c double bonds of chalcones
Tripathi, Vishwa Deepak,Jha, Anand Mohan
, p. 2322 - 2324 (2018/09/09)
In this article, we reported a biomimetic approach for chemoselective reduction of C=C double bonds in chalcones under metal and acid free conditions, that relies on olefin activation by hydrogen bond formation. The process requires only catalytic amount of ephedrine as hydrogen bond donor and utilizes Hantzsch esters for transfer hydrogenation.
Donor–Acceptor Complex Enables Alkoxyl Radical Generation for Metal-Free C(sp3)–C(sp3) Cleavage and Allylation/Alkenylation
Zhang, Jing,Li, Yang,Xu, Ruoyu,Chen, Yiyun
supporting information, p. 12619 - 12623 (2017/09/11)
The alkoxyl radical is an essential and prevalent reactive intermediate for chemical and biological studies. Here we report the first donor–acceptor complex-enabled alkoxyl radical generation under metal-free reaction conditions induced by visible light. Hantzsch ester forms the key donor–acceptor complex with N-alkoxyl derivatives, which is elucidated by a series of spectrometry and mechanistic experiments. Selective C(sp3)-C(sp3) bond cleavage and allylation/alkenylation is demonstrated for the first time using this photocatalyst-free approach with linear primary, secondary, and tertiary alkoxyl radicals.
Selective Debromination and α-Hydroxylation of α-Bromo Ketones Using Hantzsch Esters as Photoreductants
Jung, Jaehun,Kim, Jun,Park, Gyurim,You, Youngmin,Cho, Eun Jin
supporting information, p. 74 - 80 (2016/01/25)
Two transformations initiated by photoinduced one-electron transfer to α-bromo ketones have been demonstrated. Hantzsch esters donate one electron to α-bromo ketones under photoirradiation, promoting reductive debromination. Subsequent reactions of the resulting radical species of the ketones with molecular oxygen and Hantzsch esters lead to α-hydroxylation or debromination, respectively. The relative dominance of the two pathways depends profoundly on the reaction conditions, including solvent, O2 levels, and the concentration of the Hantzsch esters. The synthetic protocols feature advantages because they require the environmentally benign sources, molecular oxygen and visible light.
Alginic acid: A highly efficient renewable and heterogeneous biopolymeric catalyst for one-pot synthesis of the Hantzsch 1,4-dihydropyridines
Dekamin, Mohammad G.,Ilkhanizadeh, Siamand,Latifidoost, Zahra,Daemi, Hamed,Karimi, Zahra,Barikani, Mehdi
, p. 56658 - 56664 (2015/02/02)
Alginic acid, a naturally occurring polysaccharide, in its granular form and without any post-modification was found to be an efficient, environmentally benign, easily recoverable and low-cost catalyst for the clean and rapid synthesis of 1,4-dihydropiridine derivatives (DHPs) just based on its polysaccharide architecture. The Hantzsch pseudo-four-component reaction of ethyl or methyl acetoacetate, ammonium acetate and different aldehydes is catalyzed by alginic acid efficiently under mild conditions to afford the desired products in high to quantitative yields and clean reaction profiles. Avoiding the use of any transition metal, the use of a one-pot and multi-component procedure for the synthesis of DHPs, the reusability of the catalyst and operational simplicity are important features of this methodology.
Synthesis, anticonvulsant activity and molecular properties prediction of dialkyl 1-(di(ethoxycarbonyl)methyl)-2,6-dimethyl-4-substituted-1,4- dihydropyridine-3,5-dicarboxylates
Prasanthi,Prasad,Bharathi
, p. 97 - 104 (2014/01/17)
The synthesis and anticonvulsant properties of new N-diethylmalonyl derivatives of nifedipine and other isosteric analogues (7a-7n) were described. Anticonvulsant screening was performed by subcutaneous pentylenetetrazole (scPTZ) and maximal electroshock (MES) induced seizures tests. Majority of the compounds were effective in scPTZ and MES screens. Compound 7k showed good activity displaying maximum protection, which may be due to the presence of styryl moiety at position 4 of 1,4-dihydropyridine nucleus and the methyl groups of diester functionality. Compounds 7a-7d, 7g, 7i and 7k obeyed the Lipinski's "rule of five" and have drug-likeness. Based on computational prediction of molecular and pharmacokinetic properties, it was found that the compounds have good oral absorption.
1-Methylimidazolium trifluoroacetate [Hmim]Tfa: Mild and efficient Bronsted acidic ionic liquid for Hantzsch reaction under microwave irradiation
Avalani, Jemin R.,Patel, Devji S.,Raval, Dipak K.
, p. 1091 - 1096 (2013/03/13)
One pot synthesis of 1,4-dihydropyridine derivatives was achieved via condensation of various β-ketoesters with aromatic/aliphatic aldehydes and ammonium acetate. The reaction was catalysed by a stable and reusable Bronsted acidic ionic liquid (IL), 1-methyl-imidazolium trifluoroacetate ([Hmim]Tfa), under microwave (MW) irradiation. The synergistic combination ofMWwith IL can potentially go a long way tomeet the increasing demand for chemical processes. This homogeneous catalytic procedure is simple and efficient. The catalyst can be reused at least four times with almost complete retention in its activity. Indian Academy of Sciences.
Laccase-catalyzed oxidation of Hantzsch 1,4-dihydropyridines to pyridines and a new one pot synthesis of pyridines
Abdel-Mohsen, Heba T.,Conrad, Juergen,Beifuss, Uwe
supporting information, p. 2686 - 2690,5 (2020/09/14)
The laccase-catalyzed oxidation of 1,4-dihydropyridines to pyridines using aerial O2 as the oxidant exclusively delivers pyridines with yields up to 95% under mild reaction conditions. Combination of the Hantzsch 1,4-dihydropyridine synthesis with the newly developed laccase-catalyzed oxidation forms the basis of a facile and environmentally benign method for the synthesis of pyridines in one pot.
One-pot synthesis of hantzsch dihydropyridine catalyzed by ionic liquid (BmimOAc) and the oxidative aromatization of dihydropyridine using FeCl 3·6H2O
Liu, Ruidong,Zhang, Jian
experimental part, p. 1743 - 1746 (2011/12/22)
A series of 1,4-dihydropyridines were synthesized in one pot synthesis with the yield of 80-93 % using ionic liquid [bmim]OAc as catalyst and DMF as solvent. The ionic liquid could be repeatedly utilized 5 times with no decrease of the yield. The aromatization of these dihydropyridines (4a, 4b, 4d, 4f, 4h and 4i) were executed by the action of iron chloride and the post-processing was simplified using ethanol instead of water in dissolving dihydropyridines.
